This means that the pattern described in the file subcat.pat was found 6 times in the corpus, each item gives the sentence identifier and the position of nodes matched by the pattern.

Note that two other options exist (-html and -dep_dir <directory>).
The first one produces a new html field in each JSON item with the sentence where words impacted by the pattern are in a special HTML span with class highlight.
The second one produces a new file in the folder directory with the representation of the sentence with highlighted part (as in Grew-match tool) and a new field in each JSON item with the filename; the output is in dep format (usable with Dep2pict).